Electric baseboard heat storage means



Nov. 1, 1966 c. D. SNELLING 3,283,125

ELECTRIC BASEBOARD HEAT STORAGE MEANS Filed Oct. 21, 1964 5 Sheets-Sheet l AIRFLOW 2 FIG'I assa- 7 AIR FLOW 7 AIR FLOW +1 A HEAT STORAGE MATERIAL /9 A9 l9 2 ll FIG.2 s k 4 4 FIG.3

HEAT STORAGE MATERIAL H FIG.4

(gig) INVENTOR.

CHARLES D. SNELLING ATTORNEYS Nov. 1, 1966 Filed Oct. 21, 1964 T E M PER AT U R E c. D. SNELLING 3,283,125

ELECTRIC BASEBOARD HEAT STORAGE MEANS 5 Sheets-Sheet 2 34 {i 32 1 F|G.6A HEAT STORAGE 4 MATERIAL T I M E INVENTOR.

CH ARLES D, SNELLING BY f6 Z 0 2: W ATTORNEYS Nov. 1, 1966 c. D. SNELLING 3,283,125

ELECTRIC BASEBOARD HEAT STORAGE MEANS 5 Sheets-Sheet 3 Filed Oct. 21, 1964 NTUE INVENTOR. CHARLES D- SNELLING ATTORNEYS.

United States Patent 3,283,125 ELECTRIC BASEBQARD HEAT STURAGE MEANS Charles D. Snelling, 29 9 Greenleaf St, Allentown, Pa. Filed Oct. 21, 1964, Ser. No. 405,489 3 Claims. (Cl 219365) This application is a continuation-in-part of my application Serial No. 320,310, filed October 31, 1963, now abandoned.

The present invention relates to a baseboard heating unit and, in particular, to a baseboard electric heating unit capable of maintaining a substantially more uniform flow of heat than prior heaters to an area being heated with minimum temperature fluctuation.

The use of electrical energy as a source of heat in the home has led to the development of small compact baseboard units, so called because they are adapted to be mounted against the baseboard of a wall of a room to be heated. Like the baseboard, the unit is longitudinally configurated except that it is hollow and has enclosed therein a longitudinally arranged electric heating element which is connected into an electric circuit in the usual conventional manner. Baseboard heaters are generally automatic and are operated by a thermostat strategically located in a room or other area being heated. Such heaters may be 6 inches high, about 2 and inches deep and 2 to 3 feet long, or as long as 8 feet, or even possibly longer. The heating. element may comprise the usual 80 nickel-20 chromium electrical heat resistance element completely enclosed within a metal sheath, e. g. a tube, the heating element being buried in an insulating material, such as powdered magnesia or the like, for example similar to a Calrod unit.

Generally, heat exchanger fins surround the heating elements in order to assure optimum heat transfer efliciency, especially in the case where the baseboard heating unit works on the convection principle. The heating is effected by either one of two ways: by the flow of air through the bottom opening of a grill, around the finned heating element and then through the top opening of 'the grill work out into the room; or by heat reflection olt a reflecting unit mounted inside the baseboard unit on the back side thereof behind the heating element. The convection type appears to be the more popular one in use today.

As stated above, the baseboard units are generally automatically controlled by means of a thermostat. Because the elements are not capable of maintaining or storing a high heat content, they are usually designed to throw off a relatively high amount of heat in a short time period. Thus, when the thermostat operates to shut off the electric power, the heating unit immediately cools down and gives off no more heat until the temperature in the room drops to a value corresponding to the setting on the thermostat which actuates the power supply. Because of the time lag which is generally inherent in such a system, a temperature variation is usually noticeable in the room. It would be desirable to have a unit that would not cool down rapidly and that would continually furnish some heat, even when the power is off, so as to smooth out the temperature fluctuation and provide a more uniform heating.

I have now developed a heating unit which will overcome the foregoing difiiculties and provide a more uniform type of heating.

It is accordingly the object of my invention to provide a baseboard heating unit which is designed to store heat during a heating cycle and release heat during the ofi cycle.

Another object is to provide a baseboard heating unit having a heat storage element in cooperable association with an electric heating element adapted to retain heat for release during an olf cycle.

These and other objects will more clearly appear when taken in conjunction with the following description and the accompanying drawing, wherein:

FIG. 1 shows in front view a portion of a baseboard heating unit of an air convection type;

FIGS. 2 and 3 are transverse views taken along the lines 2-2 and 3-3, respectively, of FIG. 1;

FIG. 4 is illustrative of one embodiment of a heating element for use with a baseboard of the type shown in FIGS. 1 to 3;

FIGS. 5 and 6 illustrate another embodiment of a baseboard heating unit of the heat-reflective type incorporating the novel features of my invention;

FIG. 6A is a cross section taken along line 6A-6A of FIG. 6;

FIG. 7 depicts temperature curves showing the kind of temperature control obtainable at the air outlet of the baseboard heating units of my invention as compared to the temperature control obtained by the more conventional unit;

FIGS. 8 and 9 show a still further embodiment of a heating unit for use with a baseboard of the type shown in FIGS. 1 to 3;

FIGS. 10 and 11 depict one type of heating element employed in the heating unit of FIG. 8, and

FIG. 12 shows in partial cross section an end view of a baseboard heater illustrating the mounting employed in supporting the heating unit of FIG. 8.

Stating it broadly, my invention comprises a baseboard heat storage and heat releasing unit comprising an elongated housing having a grill on the front side thereof, and an electric resistance heater supportably disposed within and along said housing with an elongated heat storage modular element disposed in heat absorbing relation with the electric heater. The modular element is formed of a hollow longitudinal member having encapsulated therein a chemical heat storage material characterized by a relatively high heat of transition. By heat of transition is meant the heat energy exchange which occurs when a chemical heat storage material undergoes a phase change, for example, a crystallographic change in the solid state, or a change of state going from the liquid phase to a solid phase, or vice versa.

Any one of a variety of heat storage materials may be employed in carrying out my invention. A material I may employ is anhydrous sodium sulfate which has a transition temperature of about 450 F. and a heat of transition in the solid state from one crystal form to another of about 128 B.t.u.s per pound. Another is anhydrous sodium molybdate which has a transition temperature of about 820 F. and a heat of transition in the solid state from one crystal form to another of about 128 B.t.u.s per pound.

An example of a material having a heat of transition based on a liquid to solid phase change is trisodium phosphate dodecahydrate (Na PO .12H O). The foregoing material has a latent heat of fusion or phase change of approximately B.t.u.s per pound available for heat transfer at a melting temperature between to 180 F., provided there are no variations in its crystallization as it gives up its latent heat. A particularly useful composition is one comprising 31 to 34% trisodiumphosphate, about 4 to 7% sodium hydroxide and the balance water which has a melting point of about F. When the solid material is heated to 155 F., it dissolves in its own water of crystallization and when it is cooled to just below 155 F. it crystallizes or solidifies and gives off an amount of heat corresponding to about 100 B.t.u.s per pound. Examples of other heat storage materials are lead acetate [(PbC H O .3H O] which melts at 167 F., Na S O .5I-I O which melts at 120 F. and exhibits a latent heat of transition of about 86 B.t.u.s per pound, NaCH COO.3I-I O which melts at 137 F. and exhibits a latent heat of transition of about 144 B.t.u.s per pound, and others.

I desire to use anhydrous sodium sulfate because in the solid state it is capable of storing heat over the range of 300 F. to 600 F. as sensible heat and energy of phase change, that is energy of crystal transition. Moreover, working with materials in the solid state minimizes corrosion and containment problems.

By having a heat storage modular element disposed in heat absorbing relation with the primary heating element, some of the heat is stored as heat of transition, such that when the primary heating element is shut off by the thermostat, the baseboard heater cools slowly rather than rapidly as heretofore. The heat storage element, having a high heat content, gives off its sensible heat until the temperature reaches the point at which the phase change of the contained heat storage material occurs after which it gives up its heat of transition. Instead of obtaining a rapid fluctuation of the temperature during the off cycle, a sort of temperature modulation results as illustrated in FIG. 7 which depicts qualitatively the fluctuation of temperature with time of air leaving the outlet of a thermostatically controlled heater. Two curves are shown, one where the baseboard heater does not contain a heat storage element (Curve A) and the other (Curve B) where the baseboard heater contains a heat storage element. It will be noted that a broader band of temperature fluctuation is indicated (Curve A) with a baseboard heater outside the invention as compared to a more modulated temperature variation (Curve B) indicated with the baseboard heater or assembly of the invention.

Referring now to FIGS. 1 to 3, I show a portion of a convection type baseboard heater comprising an elongated housing designated generally by the numeral 1 having a back side 2 for mounting against the base of a wall, top and bottom flanges 3 and 4, respectively, integral with the back side and a grill 5 on the front side thereof, said grill defining top and bottom openings 6 and 7, respectively, which cooperate with other elements with in the housing to provide a convective flue for air flow into and out of the baseboard heater as shown in FIG. 3.

Referring to FIG. 3, which is a transverse section taken along line 33 of FIG. 1, bottom flange 4 is shown integral with back side 2, the flange terminaating into a bent portion 8 which extends inwardly of said housing to provide a convection path rearwardly of a partition 9 which is configurated as an inverted L section extending longitudinally of said housing between the back side thereof and grill 5.

Grill 5, forming the front face of the baseboard heater shown in FIG. 3, comprises two spaced apart elements 5a and 5b whereby to provide a path for the fiow of air therebetween to keep the front grill portion from overheating. In this embodiment of the invention, the electrical resistance heating element and the heat storage modular element are formed into the heat assembly shown generally by the numeral 10 (note FIGS. 2, 3 and 4) wherein the modular element 11 is held adjacent to and in heat absorbing relation with heating element 12 by means of heat exchanger fins 13 of aluminum or other heat conductive metal. The heating element comprises a metal sheath which has within it an electrical resistance element 14 which is insulated from the sheath by a powdered refractory 15 such as magnesia and is connected by conventional means (not shown) to a source of power. The heating element and heat storage modular assembly is supported within the housing at the end walls, for example, at end wall 16 via U-shaped saddles 17 and 18, respectively, which extend inwardly from the end wall as shown in FIG. 1. The modular element embodiment shown in FIGS. 2 to 4 comprises a hollow member having a rectangular cross section and having encapsulated therein a heat storage material 19, such as anhydrous sodium sulfate. It is desirable that the material of construction be corrosion resistant to the wide variety of the contained heat storage materials which may be employed. Such construction materials may comprise stainless steel, nickel, the nickel alloy known by the trade mark Inconel or other suitable material of construction. Preferably the modular element shown in FIGS. 1 to 4 should have a dark surface so as to absorb heat efficiently from the heating element. Where a metal sheath is used for the modular element, the surface should preferably have a black oxide coating to insure eflicient heat absorption from the heating element. As stated hereinabove, baseboard heaters are usually controlled by a thermostat which is not shown in the drawing since its use in combination with electric heaters is well known to those skilled in the art.

The convection flow of air into and out of the housing of the heater is illustrated in FIG. 3 which shows the main flow of air as depicted by the broad arrows as going around the finsof the heating element and, the heat storage modular element. Minor flow paths of the air are also shown, one between elements 511 and 5b and the other rearwardly of partition 9. The minor flow path of air keeps the front and back side of the baseboard from overheating while at the same time conducts some heat from the heater into the room, while the major flow of air about the heat exchanger fins 13 removes a good portion of the heat being generated.

My invention as applied to another baseboard heater of the heat-reflective type is shown in FIGS. 5 and 6 as also comprising an'elongated housing designated genera lly by the numeral 20 comprising back side 21 adapted to be secured to and along the base of a wall and a grill 22. The grill is formed of slender elements 23 of stainless steel, aluminum or other suitable material running ion-gitudinally of said housing and slender transverse elements v24 running across the face of the grill and abuttingly assured to elements 23 at their points of contact by resistance welding or other suitable means. The grill face is adapted to be spring fitted to the back side of the housing as shown in FIG. 5 at 25 and 26, respectively.

Attached to the back side within the housing is a longitudinal reflector plate 27 of polished metal, such as sheet aluminum or chromium plated sheet metal. Suspended forwardly of said reflector and behind the grill is an electric resistance heating unit 28 supported by insulated means 29 projecting from the top and bottom of the housing and along thereof, the opposite ends of the electric heat-ing resistant unit being adapted for connection (not shown) to a source of power. As in the first embodiment, a heat storage modular element 30 is provided between the reflector 27 and the heating unit 28, the modular element being supported by means projecting from an end wall 31 of the housing. The supporting means may comprise a saddle 32 (shown :behind the end wall flange 33, in FIG. 6) formed as a U-shape as shown more clearly in FIG. 6A.

The heat storage material 34 encapsulated in the modular element may be the same as that used in the em bodiment shown in FIGS. 1 to 4. As in the first embodiment, the thermostatically controlled electric heat resistance unit throws off heat which, in this case, is reflected into the room being heated. Some of the heat is absorbed by the heat storage modular element and stored as latent heat of transition which it gives off during the off cycle, thereby minimizing temperature fluctuation in the room between the on and off heating cycle.

In FIGS. 8 to 12, I show as another embodiment a heating unit in which the heating element is encased within the heat storage modular element to insure optimum heat absorption by the heat storage material. The elongated modular element is substantially rectangular in cross section. The outside casing of the modular element is formed of an extruded channel 35 of aluminum having a pair of inwardly projecting shoulders 36, 37 running longitudinally of the channel. Each of the shoulders is longitudinally grooved (38, 39) and receives therein a plate or sheet 40 of aluminum therealong to complete the enclosure of the modular element. Cooling fins 41 in the shape of a T project outwardly from the surface of fitted plate along the whole length of the element. The modular element is enclosed at its end 42 by a cap 43, the opposite end being similarly capped but being left exposed for purposes of clarity. The modular element is filled with a heat storage material 44, such as anhydrous sodium sulfate, and has embedded in it an electrical resistance heating element 45 which is encased in a protective sheath of stainless steel 46 filled with an insulating material, such as magnesia, which completely surrounds the heating element. The whole element, including the sheath, is bent into a U shape as shown in phantom in FIG. 8 and as shown in FIG. 10. The ends of the electrical resistant element are connected to terminals 47, 48 which in turn are connected to power lines, not shown.

The electrical heat resistance elements are preferably assembled as shown in FIG. 10. The loop of the element at 49 is reinforced by means of a bracket 50 using sheet metal which is form-fitted about the loop. Vanes 51 are provided comprising sheet metal aluminum or other suitable ine-tal of high thermal conductivity with the sides cylindrically formed for slipping over the legs of the heating element as shown in FIG. (note also FIG. 11). A pair of guide members 52, 53 are riveted to the back of the vanes via rivets 54. The purpose of the guides is to help position the electrical resistance heating element Within the modular heat storage element. In mounting the modular element 35 within the baseboard of the type shown in FIGS. 1 to 3, a C-shaped hanger 55 is employed which connects via an overhang 58 to a bracket mount 56 attached to the back of the rear wall 57 of the baseboard heater as shown in FIG. 12. The C-shaped hanger is configurated to receive and support the modular heat storage element and projecting fins 41 in back of grill or front face 5 as depicted in FIG. 12.

It is apparent from the foregoing that I provide a novel baseboard heating element which overcomes the disadvantages of the conventional heaters by providing more uniform heating while minimizing temperature fluctuations between heating cycles in the immediate area being heated.

In effect, my novel baseboard heating element operates as a modulating and temperature averaging device, that is, With my device there is less thermal variation at the heater When the power is olf as compared to the conventional baseboard heater, even though the baseboard heater operates at a slower initial warm-np. However, the slower warm-up is advantageous as it inhibits overshoot of temperature (note FIG. 7). For example, in the spring, the air flowing out of the baseboard heater may range in temperature from 105 to 130 F. with the conventional baseboard heater, the device cools rapidly the moment the power is shut oif, whereas, with my device, because of its high heat content, heat is continuously being delivered on the off-cycle while the room is losing heat. In the dead of winter when the temperature of the air leaving the baseboard ranges from 165 to 170 F., my device maintains a balance of heat output during the chi cycle, while with the conventional baseboard heater the temperature of the air leaving the heater falls markedly the moment the power is shut off thermostatically. This noncontinuous type of heating results in marked temperature 6 variations within a room leading in many instances to discomfort.

Although the present invention has been described in conjunction with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Such modifications and variations are considered to be Within the purview and scope of the invention and appended claims.

It is claimed:

:1. In a continuously cyclically operable convectiontype baseboard heating unit wherein the heat evolve-d therefrom undergoes rather abrupt changes in heat flow during oft-cycles, the improved combination of a baseboard heating unit and thermal moderator comprising, an elongated housing having a back side for mounting against the 'base of a wall, a grill on the front side of said housing having top and bottom openings therealong for allowing free flow of air into and out of the unit by convection, a thermal moderator comprising an elongated hollow rectangularly shaped modular element supportably disposed within and along said housing in spaced relationship to said back side and said grill, said modular element having encapsulated therein a solid anhydrous chemical heat storage material characterized by a relatively high heat of transition in the solid state from one crystal form to another, a protectively sheathed primary electric resistance heater secured to an elongated metal backing member of high thermal conductivity encased within said hollow element and surrounded by said chemical heat storage material, said resistance heater and backing member being oo-extensive and extending substantially the full length of said modular element, the backing member being of such width as to extend across at least the major portion of the height of the modular element, vertical heat exchanger fins directly connected in thermal conductive relationship to and along substantially the entire length of at least the front face of said heat storage modular element behind the grill of said baseboard heater, whereby a relatively even flow of heat is convectional-ly maintained from the baseboard heating unit by virtue of continuous flow of heat from the modular element during off-cycles of said primary resistance heater.

.2. The baseboard heating unit of claim 1 wherein the vertically disposed fins are T-shaped in transverse cross section.

3. The baseboard heating unit of claim 1 wherein the electric resistance heater secured to the backing member is U-shaped, the legs of which run along the upper and lower edges of said backing member.

References Cited by the Examiner UNITED STATES PATENTS 1,919,204 7/1933 Decker 219-341 2,000,438 5/1935 Dougherty 2l9365 2,022,812 12/1935 Roe 21936-5 2,066,127 12/1936 Slayter 21934 1 2,702,334 2/1955 Kleist 219-345 2,938,101 5/1960 'Borzner 2 19365 2,949,679 8/1960 MacCracken 219365 X FOREIGN PATENTS 1,300,946 7/1962 France.

ANTHONY BARTIS, Primary Examiner. RICHARD M. WOOD, Examiner. 

1. IN A CONTINUOUSLY CYCLICALLY OPERABLE CONVECTIONTYPE BASEBOARD HEATING UNIT WHEREIN THE EVOLVED THEREFROM UNDERGOES RATHER ABRUPT CHANGES IN HEAT FLOW DURING OFF-CYCLES, THE IMPROVED COMBINATION OF A BASEBOARD HEATING UNIT AND THERMAL MODERATOR COMPRISING, AN ELONGATED HOUSING HAVING A BACK SIDE FOR MOUNTING AGAINST THE BASE OF A WALL, A GRILL ON THE FRONT SIDE OF SAID HOUSING HAVING TOP AND BOTTOM OPENINGS THEREALONG FOR ALLOWING FREE FLOW OF AIR INTO AND OUT OF THE UNIT BY CONVECTION, A THERMAL MODERATOR COMPRISING AN ELONGATED HOLLOW RECTANGULARLY SHAPED MODULAR ELEMENT SUPPORTABLE DISPOSED WITHIN AND ALONG SAID HOUSING IN SPACED RELATIONSHIP TO SAID BACK SIDE AND SAID GRILL, SAID MODULAR ELEMENT HAVING ENCAPSULATED THEREIN A SOLID ANHYDROUS CHEMICAL HEAT STORAGE MATERIAL CHARACTERIZED BY A RELATIVELY HIGH HEAT OF TRANSITION IN THE SOLID STATE FROM ONE CRYSTAL FORM TO ANOTHER, A PROTECTIVELY SHEATHED PRIMARY 